Double piston for a compressor

ABSTRACT

A double piston for a compressor, having an elongated piston carrier which has one piston on each end, and having a connecting rod, extending approximately parallel to the piston carrier, that is supported rotatably by means of a bearing on a bolt of the piston carrier and spaced apart from it is supportable on a cam of a drive mechanism by means of a connecting rod bearing. In a middle region that extends between the two pistons, the piston carrier includes an intermediate chamber, dimensioned to receive the connecting rod freely movably, in which the connecting rod is received freely movably.

BACKGROUND OF THE INVENTION

A double piston of this type for a compressor is known (European Patent Disclosure 12 33 183 A1), whose connecting rod in the case of a compressor is located between the outlet of a drive mechanism and the piston carrier, so that by way of the connecting rod, the rotary, eccentric power takeoff motion of the drive mechanism can be converted into a reciprocating motion of the double piston. It has been demonstrated that during the course of motion of the piston, vibration occurs in the piston and in the valves of the compressor and is transmitted via the connecting rod and the connecting rod bearing. Vibration originating in the drive mechanism and its cam also occurs. This vibration can cause premature bearing damage because of the mechanical strains and moreover has the disadvantage of causing irritating noise, which is especially unpleasant when such compressors are installed in vehicles, for instance.

SUMMARY OF THE INVENTION

The object of the invention is to embody a double piston of the type defined at the outset in such a way that when it is installed in a compressor, any vibration that occurs is damped, and resultant noise is at least reduced, with an attendant increase in efficiency and in the length of the life of the bearings.

In a double piston of the type defined at the outset, this object is attained according to the invention by the characteristics recited in claim 1. Because of this symmetrical disposition of the connecting rod relative to the piston carrier and its pistons, no transversely oriented forces, but only forces within the plane of symmetry, are operative in the region of the connecting rod bearing. As a result, the load on the connecting rod bearing is reduced and its service life is lengthened. Moreover, because of reduced stress on the bearing, efficiency is also enhanced. Advantageously, this also brings about vibration damping, with the result that noise that would otherwise occur is reduced solely by this provision. Hence a compressor equipped such a double piston is especially well suited to installation wherever low noise is especially important, such as in vehicles. The design is simple, economical, and safe in operation.

Other particular characteristics and features of the invention will become apparent from the other claims. Because of the at least one vibration-damping bearing receptacle which in the course of the connecting rod is located between the connecting rod bearing and the coupling point, the vibration damping is improved still further, so that noise is reduced multiple times compared to what would otherwise occur.

Further details and advantages of the invention will become apparent from the ensuing description.

The complete wording of the claims is not given above solely for the sake of avoiding unnecessary repetition; instead, merely by mentioning the claims, they are referred to, but all the characteristics of the claims are considered at this point to be expressly disclosed in a way that is essential to the invention. All the characteristics mentioned above and in the ensuing description as well as all the characteristics that can be taken solely from the drawing are further components of the invention, even if they are not especially emphasized and in particular even if they are not mentioned in the claims.

The invention is described in further detail below in terms of an exemplary embodiment shown in the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic section through a double piston engaged by a connecting rod of a compressor not otherwise shown; and

FIG. 2 shows half of a schematic cross section taken along the line II-II in FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The drawings show a piston 10 of a compressor not otherwise shown, such as a high-performance compressor, that can be put together with an electric drive motor, not shown, analogously to EP 12 33 183 A1, for instance, to make a functional unit. The piston 10 is embodied as a double piston, which has an elongated piston carrier 11 that on one end has a first piston 12 of large diameter for a first pressure stage and on the diametrically opposite end has a second piston 13 of smaller diameter for a second pressure stage. Because of this design of the piston 10 as a double piston, the compressor not otherwise shown is two-staged. The piston carrier 11, together with one or both pistons 12, 13, forms an integral component, embodied for instance as a molded part of plastic or die cast aluminum.

The piston 10 and in particular its piston carrier 11 is driven by means of a connecting rod 14, which is rotatably supported on a cam 15 on the end of a shaft 16 by means of a bearing 17, such as a ball bearing, hereinafter referred to as the connecting rod bearing 17. The shaft 16 is part of the drive mechanism in form of the electric drive motor not further shown, such as a high-powered motor.

The connecting rod 14 extends approximately parallel to the piston carrier 11 and approximately perpendicular to the longitudinal center axis of the shaft 16. The connecting rod 14 can be coupled pivotably, in particular rotatably, on the bolt 18 by means of a bearing 19, such as a ball bearing. The bearing 19 is seated with its inner ring solidly on the bolt 18, while its outer ring is received in the connecting rod 14 in a manner fixed against relative rotation.

In a middle region 31 that extends between the two pistons 12, 13, the piston carrier 11 has an intermediate chamber 32, dimensioned for receiving the connecting rod 14 freely movably, in which the connecting rod 14 is received freely movably. Here, the piston carrier 11 has two webs 33 and 34, extending approximately longitudinally and approximately parallel to one another, which are united integrally with the pistons 12 and 13 in the region of them. Between the webs 33 and 34, the intermediate chamber 32 is formed and the connecting rod 14 is received. As FIG. 1 shows, the intermediate chamber 32 extends approximately within a plane 35 that is aligned with a diametral plane 36 of one piston 12 and a diametral plane 37, aligned with the latter diametral plane, of the other piston 13 in such a way that these planes 35 through 37 extend in one line. The plane 35 essentially represents the longitudinal plane of symmetry of the piston carrier 11. The connecting rod 14 is placed in the intermediate chamber 32 in such a way that it extends substantially within this plane 35.

The connecting rod 14 is embodied as a rectilinear component, whose connecting rod bearing 17 and bearing 19 are located within a common longitudinal center plane, which coincides approximately with the plane of symmetry of the piston carrier 11. The bolt 18 of the piston carrier 11 penetrates the intermediate chamber 32, extending transversely to the plane of symmetry 35, and is received by both ends in the transversely spaced-apart webs 33 and 34 of the piston carrier 11, in particular being fixedly located there. The webs 33, 34 of the piston carrier 11, together with the bolt 18, form a bearing fork for the end there of the connecting rod 14, which is received between them and is retained with the bearing 19 on the bolt 18, while the remainder of the connecting rod 14 extends freely into the intermediate chamber 32. As a result of this special disposition of the centrally placed connecting rod 14, the bearings 17 and 19 are loaded only with forces acting within the plane 35, and not with any forces oriented transversely thereto. As a result, the service life of the bearings 17, 19 is increased, and efficiency is furthermore improved. It is also advantageous that as a result, a noise reduction is also achieved in the region of the bearings 17, 19.

The connecting rod bearing 17 is seated with its inner ring firmly on the cam 15. In the course of the connecting rod 14 between the connecting rod bearing 17 and the coupling point with the bearing 19, there is at least one vibration damper 20, which is provided in the region of the coupling point, such as the bearing 19 at that location, and/or—as shown in FIG. 1—in the region of the connecting rod bearing 17. This vibration damper 20 has a vibration-damping bearing receptacle 21, which has a vibration-damping layer 22 that is elastic, being formed in particular of rubber, synthetic rubber, or the like. The vibration-damping layer 22 has a hardness of for instance approximately 80\ Shore A.

In the exemplary embodiment shown in FIGS. 1 and 2, the vibration-damping bearing receptacle 21 has a rubber spring, while in the other exemplary embodiment, not shown, the bearing receptacle 21 may be formed solely of the vibration-damping layer 22. In that case, the connecting rod bearing 17 is embedded with its outer ring directly in the vibration-damping layer 22, which in turn is located in a receptacle 23, in particular a bore, in the connecting rod 14. In the embodiment of the bearing receptacle 21 as a rubber spring, as shown, this rubber spring has two concentric rings 24 and 25, in particular of metal, and between the rings 24, 25 it has the layer 22, extending annularly, which is embodied for instance as an integrally vulcanized-on rubber layer. By means of the vibration-damping bearing receptacle 21, the connecting rod bearing 17 is embedded in the receptacle 23 of the connecting rod 14. The disposition of the vibration damper 20 at this point has proved to be especially advantageous. The vibration-damping layer 22 can advantageously be designed such that it has greater elasticity in the circumferential direction than in the radial direction.

In another exemplary embodiment not shown, the bearing 19 of the coupling point may also be embedded by means of a vibration-damping bearing receptacle, analogous to the bearing receptacle 21, in the connecting rod 14 and/or in part of the piston 10, such as the piston carrier 11.

Because of the disposition of the at least one vibration damper 20, very good damping of vibration that occurs during the course of motion of the piston 10 and is transmitted via the connecting rod 14 and the bearings 17 and 19 and that on the other hand occurs as a result of the drive mechanism not further shown and the cam 15 is attained. Such vibration not only stresses the bearings but also causes irritating noise, which is especially unpleasant if compressors embodied in this way are installed in vehicles, for instance. Thus because of the vibration damper 20, such vibration in the region of the bearing receptacle 21 is absorbed and damped by the layer 22, as a result of which a further reduction in noise, in fact by multiple times, is achieved. 

1. A double piston for a compressor, having an elongated piston carrier (11), which has one piston (12, 13) on each end, and having a connecting rod (14), extending approximately parallel to the piston carrier (11), which is coupled rotatably to the piston carrier (11) by means of a bearing (19) and is supportable, spaced apart from the coupling point, on a cam (15) of a drive mechanism by means of a connecting rod bearing (17), wherein the piston carrier (11), in a middle region (31) that extends between the two pistons (12, 13), has an intermediate chamber (32), dimensioned for receiving the connecting rod (14) freely movably, in which the connecting rod (14) is received freely movably.
 2. The double piston as recited in claim 1, wherein the piston carrier (11) has two webs (33, 34), extending approximately longitudinally and approximately parallel to one another, between which the intermediate chamber (32) is formed and the connecting rod (14) is received.
 3. The double piston as recited in claim 1, wherein the intermediate chamber (32) extends approximately within a plane (35) that is aligned with a diametral plane (36) of one piston (12) and a diametral plane (37), aligned with the latter diametral plane, of the other piston (13) and essentially represents the longitudinal plane of symmetry of the piston carrier (11), and the connecting rod (14) extends substantially within this plane (35).
 4. The double piston as recited in claim 1, wherein the connecting rod (14) is embodied as a rectilinear component, whose connecting rod bearing (17) and bearing (19) are located within a common longitudinal center plane, which coincides approximately with the plane of symmetry (35) of the piston carrier (11).
 5. The double piston as recited in claim 1, wherein the connecting rod (14) is retained with the bearing (19) on a bolt (18) of the piston carrier (11), and the bolt (18), extending transversely to the plane of symmetry (35), penetrates the intermediate chamber (32) and is received by both ends, and in particular is located fixedly, in the transversely spaced-apart webs (33, 34) of the piston carrier (11).
 6. The double piston as recited in claim 5, wherein the spaced-apart webs (33, 34) of the piston carrier (11), together with the bolt (18), form a bearing fork for one end of the connecting rod (14), which is received between them and is retained with the bearing (19) on the bolt (18), while the remainder of the connecting rod (14) extends freely into the intermediate chamber (32).
 7. The double piston as recited in claim 1, wherein a vibration damper (20) is located in the course of the connecting rod between the connecting rod bearing (17) and the coupling point (bearing 19).
 8. The double piston as recited in claim 7, wherein the vibration damper (20) is provided in the region of the connecting rod bearing (17).
 9. The double piston as recited in claim 7, wherein the vibration damper (20) has a vibration-damping bearing receptacle (21).
 10. The double piston as recited in claim 9, wherein the vibration-damping bearing receptacle (21) has a vibration-damping layer (22).
 11. The double piston as recited in claim 10, wherein the vibration-damping layer (22) of the bearing receptacle (21) is elastic, formed in particular of rubber, synthetic rubber, or the like.
 12. The double piston as recited in claim 1, wherein the vibration-damping layer (22) has a hardness of 80\ Shore A.
 13. The double piston as recited in claim 1, wherein the bearing receptacle is formed solely of the vibration-damping layer (22).
 14. The double piston as recited in claim 1, wherein the vibration-damping bearing receptacle (21) has a rubber spring.
 15. The double piston as recited in claim 14, wherein the rubber spring has two concentric rings (24, 25), in particular of metal, and between the rings (24, 25) it has an annular rubber layer (22) that is for instance integrally vulcanized on.
 16. The double piston as recited in claims 1, wherein the connecting rod bearing (17) is embedded in the connecting rod (14) by means of the vibration-damping bearing receptacle (21).
 17. The double piston as recited in claim 1, wherein the bearing (19) of the coupling point is embedded in the connecting rod (14) and/or in part of the piston carrier (11) by means of the vibration-damping bearing receptacle (21). 